1. Field of the Invention
The presently-disclosed subject matter relates to a fitting for use in fuel gas systems and applications using the same.
2. Background Art
Fuel gas systems (e.g., propane or natural gas piping systems for distribution and metering of fuel gas to end users such as business and residential customers) are generally closed systems without ready access into the system for such purposes as: a) leak testing; b) testing of differential pressures in rotary and diaphragm meters; c) supplying gas from a cylinder to the system while maintenance is performed such as meter and regulator replacement; and d) testing operation of a relief valve.
Prior art fittings for accessing fuel gas systems have flexible seats or seals held in a housing through which access to the system requires the use of metal probes or needles which are forced through the seats and into the system. The use of lubrication between the probes or needles and the flexible seats is required when using such prior art fittings. The seats can leak below 45 degrees Fahrenheit due to memory problems. Further, such prior art fittings require the use of safety goggles and gloves because the probes can potentially “blow out” of the fitting and cause injury.
Another way that that access into the system could be provided would be by providing permanent bypass valves and associated piping in the system. However, providing such permanent bypass valves and piping is both expensive and difficult with which to work.
With respect to leak testing, fuel gas leaks, including propane and natural gas leaks, can cause serious problems from both a health and safety standpoint. For example, fires resulting from such leaks can cause both property damage and personal injury including, in some cases, death.
At present, two tests are generally required as set out in NFPA Pamphlet 54, a safety code that applies to the installation of fuel gas piping systems, appliances, equipment, and related accessories. First, a pressure test must be performed on the piping installed in a fuel gas system. The second test that must be performed is a leak test on the functional fuel gas system.
The pressure test is usually performed at 1½ times the system working pressure, but not less than 3 psig. Thus, fuel gas appliances or other devices must not be connected to the system so appliance controls are not damaged. Also, air or inert gas is used instead of the anticipated fuel to be used during normal operations. As such, the air or inert gas must generally be purged from the system prior to use of the selected fuel.
The leak test is generally performed after appliances or other such devices are attached to the fuel gas system and can be performed with the fuel gas that is used in the system. As such, the leak test is designed to test for leaks in the entire system, including the fuel delivery source location, regulators, meters, piping, and appliance control modules. Further, a leak test is also required anytime there has been an interruption in the fuel gas system (e.g., an interruption in service).
Additionally, access to fuel gas systems is required for performing testing of differential pressures in rotary and diaphragm meters, supplying gas from a cylinder to the system while maintenance is performed such as meter and regulator replacement, and testing operation of a relief valve.